Waste waters from many industrial processes, such as metal finishing, which contain a variety of metal ions some of which are toxic and some of which are valuable, are generated in large quantities. These liquids cannot be released into streams or sewers without causing environmental damage. Furthermore, such release would, in many cases, represent a violation of stringent environmental regulations. Treatment of such waters to remove the metal ions is required. Existing processes for treating such waste waters suffer from many disadvantages, among which are included high cost, production of metal-containing sludges which are difficult to treat for metal recovery and hence are dumped in landfills, complex technology, etc. The use of caustic precipitation, sulfide precipitation, electrolysis, evaporation, reverse osmosis, ion exchange, etc., are all known and suffer from one or more difficulty in terms of energy requirement, limited applicability, low absorption capacity, requirement for precise control, etc.
An attempt to use biomass of living microbes for metal recovery is reported in U.S. Pat. No. 4,293,333. T. J. Beveridge, et al. have reported that cell walls of B. subtilis will take up metals from solution (J. Bacteriol, 1976, 127(3), 1502-18). However, living microbes must be cultured, an expensive, capital-intensive process, and are subject to contamination by other microbes and inhibition by high metal concentrations or extremes of pH and other toxic components of waste streams. They are also subject to putrefaction. U.S. Pat. Nos. 4,293,334 and 4,320,093 disclose use of nonliving biomass derived from microbes but these processes display limited metal sorption or uptake capacity.